Question

State whether each of the following is true or false. If \(f a l\) se, explain why. a) By convention, method names begin with an uppercase first letter and all subsequent words in the name begin with a capital first letter. b) An import declaration is not required when one class in a package uses another in the same package. c) Empty parentheses following a method name in a method declaration indicate that the method does not require any parameters to perform its task. d) Variables or methods declared with access modifier private are accessible only to methods of the class in which they are declared. e) A primitive-type variable can be used to invoke a method. f) Variables declared in the body of a particular method are known as instance variables and can be used in all methods of the class. g) Every method's body is delimited by left and right braces ( \(\\{\text { and }\\}\) ). h) Primitive-type local variables are initialized by default. i) Reference-type instance variables are initialized by default to the value null. j) Any class that contains public static void main( String args [] ) can be used to execute an application. k) The number of arguments in the method call must match the number of parameters in the method declaration's parameter list. I) Floating-point values that appear in source code are known as floating- point literals and are type float by default.

Short answer

False, True, True, True, False, False, True, False, True, True, True, False.

Step-by-step solution

Verify Method Naming Convention

The statement says method names begin with an uppercase first letter and all subsequent words have a capital first letter. This describes PascalCase, which is typical for class names, not methods. Method names typically start with a lowercase letter and use camelCase. Thus, this statement is False.

Check Import Declaration Requirement

When one class within a package uses another class within the same package, no import declaration is required. The statement is True.

Understand Method Declaration Without Parameters

Empty parentheses in a method declaration mean no parameters are required for the method to perform its task. This is a proper usage and the statement is True.

Analyze Accessibility of Private Variables or Methods

Variables or methods with the private access modifier are only accessible within the class they are declared in. The statement correctly describes this behavior, so it is True.

Use of Primitive-Type Variable To Invoke Method

Primitive-type variables, such as 'int', 'char', etc., cannot be used to invoke methods as methods are invoked on objects. Thus, the statement is False.

Distinguish Local and Instance Variables

Variables declared within a method are local to that method, not instance variables. Instance variables are declared within the class but outside any method. The statement is False, as it describes local variables incorrectly as instance variables.

Identify Method Body Delimiters

Every method's body is indeed delimited by curly braces {}. Therefore, the statement is True.

Default Initialization of Local Variables

Local variables are not initialized by default; they must be explicitly initialized before use. Hence, the statement is False.

Default Initialization of Reference-Type Instance Variables

Reference-type instance variables are initialized by default to null. The statement is True.

Main Method for Application Execution

A class containing 'public static void main(String[] args)' can serve as an entry point for Java applications. This statement is True.

Argument and Parameter Counting in Method Calls

The method call must match in number of arguments and the parameter list in the method declaration. This statement accurately describes the proper convention, so it is True.

Identify Type for Floating-Point Literals by Default

Floating-point literals in Java are double by default, not float. So, this statement is False.

Key concepts

Method Naming Conventions

In Java, following the correct naming conventions is crucial for writing clear and maintainable code. While class names usually use "PascalCase," starting with an uppercase letter and having each new word begin with an uppercase letter, method names typically adopt "camelCase" as their standard naming convention. With camelCase:

• The first word starts with a lowercase letter.
• Subsequent words begin with an uppercase letter, like calculateSum or findMaxValue.

This approach helps distinguish methods from classes and improves readability. Breaking from these conventions could lead to confusion, especially in larger projects involving multiple team members.

Java Access Modifiers

Access modifiers in Java play a pivotal role in object-oriented programming by controlling the visibility scope of classes, methods, and variables. The primary access modifiers in Java include:

• private: Access is restricted to the class itself, ensuring encapsulation by hiding implementation details.
• default: When no modifier is specified, it allows access within the same package.
• protected: Provides access to classes in the same package or subclasses.
• public: Grants visibility to all other classes, regardless of the package.

The judicious use of these modifiers facilitates enforced encapsulation and intended interaction models between different parts of a program.

Default Initialization

Java handles default initialization differently for local and instance variables. Understanding this process helps prevent common bugs related to uninitialized variables. Here’s a key point:

• Local Variables: These variables, declared inside methods, do not have default values and must be explicitly initialized before use.

By contrast:

• Instance Variables: These are automatically initialized to default values depending on their type. For example, numeric types default to 0, boolean defaults to false, and reference types default to null.

Correct initialization guarantees predictable behavior and assists in catching logical errors early in the development process.

Java Main Method

The Java Main method is the entry point for any stand-alone Java application. It should be defined in the following way:public static void main(String[] args). Here’s what each part means:

• public: Accessible from anywhere, required to start the program.
• static: Allows Java to call this method without creating an instance of the class.
• void: Indicates that the method does not return any value.
• String[] args: An array of String objects that allows arguments to be passed to the program at runtime, which can be processed further as needed.

Defining the main method correctly ensures that the application can be executed successfully.

Primitive and Reference Types

Java categorizes data types into primitive types and reference types, which function differently. Understanding these distinctions is essential for efficient programming:

• Primitive Types: These are basic data types, such as int, char, and boolean. They are not objects and directly hold their values in memory.
• Reference Types: These are objects or arrays and store references to the actual data.

Primitive types cannot invoke methods because they aren't objects. In contrast, reference types can invoke methods, which is a key aspect of object-oriented programming that aids in modular and scalable code designs.